Expand the Material Design hover as it fades out when a ripple is triggered.

ui/views/animation/ink_drop_hover.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/views/animation/ink_drop_hover.h"
 
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/compositor/callback_layer_animation_observer.h"
 #include "ui/compositor/layer.h"
 #include "ui/compositor/layer_animation_sequence.h"
 #include "ui/compositor/scoped_layer_animation_settings.h"
 #include "ui/views/animation/ink_drop_painted_layer_delegates.h"
 
 namespace views {
 
 namespace {
 
 // The opacity of the hover when it is visible.
 const float kHoverVisibleOpacity = 0.128f;
 
 // The opacity of the hover when it is not visible.
 const float kHiddenOpacity = 0.0f;
 
 }  // namespace
 
 InkDropHover::InkDropHover(const gfx::Size& size,
                            int corner_radius,
                            const gfx::Point& center_point,
                            SkColor color)
-    : last_animation_initiated_was_fade_in_(false),
+    : size_(size),
+      explode_size_(size),
+      center_point_(center_point),
+      last_animation_initiated_was_fade_in_(false),
       layer_delegate_(
           new RoundedRectangleLayerDelegate(color, size, corner_radius)),
       layer_(new ui::Layer()) {
   layer_->SetBounds(gfx::Rect(size));
   layer_->SetFillsBoundsOpaquely(false);
   layer_->set_delegate(layer_delegate_.get());
   layer_->SetVisible(false);
   layer_->SetOpacity(kHoverVisibleOpacity);
   layer_->SetMasksToBounds(false);
   layer_->set_name("InkDropHover:layer");
-
-  gfx::Transform transform;
-  transform.Translate(center_point.x() - layer_->bounds().CenterPoint().x(),
-                      center_point.y() - layer_->bounds().CenterPoint().y());
-  layer_->SetTransform(transform);
 }
 
 InkDropHover::~InkDropHover() {}
 
 bool InkDropHover::IsFadingInOrVisible() const {
   return last_animation_initiated_was_fade_in_;
 }
 
 void InkDropHover::FadeIn(const base::TimeDelta& duration) {
   layer_->SetOpacity(kHiddenOpacity);
   layer_->SetVisible(true);
-  AnimateFade(FADE_IN, duration);
+  const gfx::Transform transform = CalculateTransform(size_);
+  AnimateFade(FADE_IN, duration, transform, transform);
 }
 
-void InkDropHover::FadeOut(const base::TimeDelta& duration) {
-  AnimateFade(FADE_OUT, duration);
+void InkDropHover::FadeOut(const base::TimeDelta& duration, bool explode) {
+  AnimateFade(FADE_OUT, duration, CalculateTransform(size_),
+              CalculateTransform(explode ? explode_size_ : size_));
 }
 
 void InkDropHover::AnimateFade(HoverAnimationType animation_type,
-                               const base::TimeDelta& duration) {
+                               const base::TimeDelta& duration,
+                               const gfx::Transform& initial_transform,
+                               const gfx::Transform& target_transform) {
   last_animation_initiated_was_fade_in_ = animation_type == FADE_IN;
 
+  layer_->SetTransform(initial_transform);
+
   // The |animation_observer| will be destroyed when the
   // AnimationStartedCallback() returns true.
   ui::CallbackLayerAnimationObserver* animation_observer =
       new ui::CallbackLayerAnimationObserver(
           base::Bind(&InkDropHover::AnimationEndedCallback,
                      base::Unretained(this), animation_type));
 
   ui::LayerAnimator* animator = layer_->GetAnimator();
   ui::ScopedLayerAnimationSettings animation(animator);
   animation.SetTweenType(gfx::Tween::EASE_IN_OUT);
   animation.SetPreemptionStrategy(
       ui::LayerAnimator::IMMEDIATELY_ANIMATE_TO_NEW_TARGET);
-  ui::LayerAnimationElement* animation_element =
+
+  ui::LayerAnimationElement* opacity_element =
       ui::LayerAnimationElement::CreateOpacityElement(
           animation_type == FADE_IN ? kHoverVisibleOpacity : kHiddenOpacity,
           duration);
-  ui::LayerAnimationSequence* animation_sequence =
-      new ui::LayerAnimationSequence(animation_element);
-  animation_sequence->AddObserver(animation_observer);
+  ui::LayerAnimationSequence* opacity_sequence =
+      new ui::LayerAnimationSequence(opacity_element);
+  opacity_sequence->AddObserver(animation_observer);
 
-  animator->StartAnimation(animation_sequence);
+  ui::LayerAnimationElement* transform_element =
+      ui::LayerAnimationElement::CreateTransformElement(target_transform,
+                                                        duration);
+  ui::LayerAnimationSequence* transform_sequence =
+      new ui::LayerAnimationSequence(transform_element);
+  transform_sequence->AddObserver(animation_observer);
+
+  animator->StartAnimation(opacity_sequence);

[varkha, 2016/04/21 16:16:49]

nit: Maybe move this above to have a full block of opacity vs. a block of
transform animation.

[bruthig, 2016/04/21 21:14:04]

Done.

+  animator->StartAnimation(transform_sequence);
 
   animation_observer->SetActive();
 }
 
+gfx::Transform InkDropHover::CalculateTransform(const gfx::SizeF& size) const {
+  gfx::Transform transform;
+  transform.Translate(center_point_.x(), center_point_.y());
+  transform.Scale(size.width() / size_.width(), size.height() / size_.height());

[varkha, 2016/04/21 16:16:49]

This is one place I think could benefit from having float scale passed around as
a parameter.

[bruthig, 2016/04/21 21:14:04]

Discussed offline.  We will defer this as per other comment.

+  transform.Translate(-layer_delegate_->GetCenterPoint().x(),
+                      -layer_delegate_->GetCenterPoint().y());
+  return transform;
+}
+
 bool InkDropHover::AnimationEndedCallback(
     HoverAnimationType animation_type,
     const ui::CallbackLayerAnimationObserver& observer) {
   // AnimationEndedCallback() may be invoked when this is being destroyed and
   // |layer_| may be null.
   if (animation_type == FADE_OUT && layer_)
     layer_->SetVisible(false);
   return true;
 }
 
 }  // namespace views